An encoder is used for sensing a position signal of motor rotation (movement), which serves as a feedback signal for motor control.
Rotary encoders fabricated utilizing a photolithography process can quickly increase the encoder counts and improve the accuracy rapidly. An optical encoder is achieved utilizing a light source to Irradiate a concave mirror and to irradiate a rotating slit plate, and the rotating slit plate has a rotation angle detection track. The optical encoder has a disc of transparent and opaque blocks. By emitting light from an LED to the disc, a plurality of light sensors are used to sample the disc, so as to obtain the location of a motor. A magnetic encoder uses the Hall-effect. The magnetic encoder has a rotatable magnetic disk and a magneto transistor/resistor. By a Hall element beside the magnet plate or the magneto-transistor/resistor, the magnet plate is sampled to obtain a position signal of the motor. A mechanical encoder has conduction and non-conduction blocks, and signals are sampled by sliding a contact block.